Event Pokémon

Shiny Pokémon, also known as alternate or rare colouration, are specific Pokémon with different colour comparing to the other Pokémon of its species. Despite not affecting battle stats, many players are keen on finding Shiny Pokémon because of their rarity and potential trade value.

Summary
Shiny Pokémon have different colouration than what is usual for its species. It is one of the many differences that a Pokémon can have within its species. The term "Shiny Pokémon", which refers to the sparkling sound effect and animation made at the start of an encounter with the ones in the games, was first created by fans. Eventually, this term fell into the official usage of The Pokémon Company.

Shiny Pokémon can differ in colour from their normal counterparts either very little or very much. Some Pokémon have a Shiny colouration only a few shades darker or lighter:

However, many Pokémon have a noticeable difference between their normal and Shiny variations. For example:

Gameplay
When a Shiny Pokémon appears in the wild or is sent out of its Poké Ball, stars will briefly surround it and make a pinging sound effect. When viewing a Shiny Pokémon's profile, a red star is indicated on the right bottom corner of the Pokémon. Being Shiny or not has no effect on the battle stats of a Pokémon, though some players believe this falsely.

Shininess is inherent to an individual Pokémon; that is, a Pokémon that starts out Shiny will always be Shiny, and one that is not will never be. Upon evolution, a Pokémon will retain its Shiny status; for example, a Shiny Charmander, if levelled up, will eventually become a Shiny Charmeleon and then a Shiny Charizard, just as a regular Charmander will become a regular Charmeleon and then a regular Charizard.

Shininess is determined by a complicated formula, which results in a probability of 16/65536 or 1/4096 of encountering Shiny Pokémon in the wild or through breeding. This probability can be enhanced by buying the Shiny Charm for 500 Robux and/or purchasing Ro-Powers for 100 Robux in-game to increase Shiny Rate for 1 hour. If both items are purchased, they will stack, making the maximum Shiny rate 1/128. There is also a method known as Chain Fishing to boost the chances of finding a Shiny Pokémon when fishing.

There are 4 ways to obtain a Shiny Pokémon:
 * Encountering a Wild Pokémon
 * Breeding and hatching a Pokémon
 * Obtaining a Pokémon in-game or from official events
 * Trading Pokémon with other players

Event Shiny Pokémon
Here is a list of Shiny Pokémon obtainable in-game during events. * The Haunter is actually a special white colour alternate colouration instead of its regular shiny form — a lighter shade of purple and a light blue mouth. However, White Haunter and its final form Halloween Gengar still retain the glittering effect when encountered or sent into battles.

Trivia

 * Shiny Pokémon were first introduced in Pokémon Gold, Silver and Crystal. This was likely to take full advantage of the capabilities of the then-recent Game Boy Color.
 * Some players are often misled that Shiny Pokémon have better stats than non-Shiny Pokémon.
 * This was once true in Pokémon Gold, Silver and Crystal due to the specified Individual Values needed for the Pokémon to be shiny, but the whole system was revamped starting from Pokémon Ruby, Sapphire and Emerald such that Shiny Pokémon are now found by using the Trainer ID and a Secret ID players cannot view in the games.
 * Some players have also mistaken some of the Pokémon with gender differences as Shiny Pokémon, most notably female Hippowdon, which is black compared to male Hippowdon's light brown.